Disk drives are an important data storage technology. Read-write heads are one of the crucial components of a disk drive, directly communicating with a disk surface containing the data storage medium. During normal operation, the read-write heads travel on an air bearing generated by their shape with respect to a nearby, rapidly rotating disk surface. Today, the disk surface typically rotates at about 4500 RPM for laptop computer disk drives and 7200 RPM for desktop computer disk drives, but the industry is moving toward much higher rotational rates. As the rotational rate of a disk surface increases, so does the wind speed acting upon the slider containing the read-write head.
Simultaneously, the Tracks Per Inch (TPI) in disk drives is rapidly increasing, leading to smaller and smaller track positional tolerances. The track position tolerance, or the offset of the read-write head from a track, is monitored by a signal known as the head Positional Error Signal (PES). Reading a track successfully usually requires minimizing read-write head PES occurrences. The effect of increasing rotational rates and TPI creates a need to minimize air flow induced turbulence around the read-write head while accessing tracks on the rotating disk surface.
FIG. 1A illustrates a typical prior art high capacity disk drive 10 including actuator arm 30 with voice coil 32, actuator axis 40, actuator arms 50–58 with head gimbal assembly 60 placed among the disks.
FIG. 1B illustrates a typical prior art, high capacity disk drive 10 with actuator 20 including actuator arm 30 with voice coil 32, actuator axis 40, actuator arms 50–56 and head gimbal assembly 60–66 with the disks removed.
FIG. 2A illustrates a suspended head gimbal assembly 60 containing the MR read-write head 200 of the prior art.
Since the 1980's, high capacity disk drives 10 have used voice coil actuators 20–66 to position their read-write heads over specific tracks. The heads are mounted on head gimbal assemblies 60–66, which float a small distance off the disk drive surface when in operation. The air bearing referred to above is the flotation process. The air bearing is formed by the rotating disk surface 12, as illustrated in FIGS. 1A–1B, and slider head gimbal assembly 60, as illustrated in FIGS. 1A–2A.
Often there is one head per head slider for a given disk drive surface. There are usually multiple heads in a single disk drive, but for economic reasons, usually only one voice coil actuator.
Voice coil actuators are further composed of a fixed magnet actuator 20 interacting with a time varying electromagnetic field induced by voice coil 32 to provide a lever action via actuator axis 40. The lever action acts to move actuator arms 50–56 positioning head gimbal assemblies 60–66 over specific tracks with speed and accuracy. Actuators 30 are often considered to include voice coil 32, actuator axis 40, actuator arms 50–56 and head gimbal assemblies 60–66. An actuator 30 may have as few as one actuator arm 50. A single actuator arm 52 may connect with two head gimbal assemblies 62 and 64, each with at least one head slider.
Head gimbal assemblies 60–66 are typically made by rigidly attaching a slider 100 to a head suspension including a flexure providing electrical interconnection between the read-write head in the slider and the disk controller circuitry. The head suspension is the visible mechanical infrastructure of 60–66 in FIGS. 1A to 2A. Today, head suspension assemblies are made using stainless steal in their suspension and beams. The head suspension is a steel foil placed on a steel frame, coated to prevent rust. It is then coated with photosensitive material. The suspension and flexures are photographically imprinted on the photosensitive material, which is then developed. The developed photo-imprinted material is then subjected to chemical treatment to remove unwanted material, creating the raw suspension and flexure.
Actuator arms 50–56 are typically made of extruded aluminum, which is cut and machined.
FIG. 2B illustrates the relationship between the principal axis 110 of an actuator arm 50 containing head gimbal assembly 60, which in turn contains slider 100, with respect to a radial vector 112 from the center of rotation of spindle hub 80 as found in the prior art.
FIG. 2C illustrates the tip of the head gimbal assembly 60 containing slider 100, with first edge 130 regarding both the principal axis 110 of the actuator and primary wind direction 120 as found in the prior art.
As those skilled in the art realize, contemporary sliders 100 may possess not only a tapered first edge 130, but may also possess a flat first edge 130. In the Figures of the patent application, the first edge 130 will shown as tapered whenever reasonable to aid the reader in understanding the invention. However, this is not being done to limit the scope of the claims.
The actuator arm assembly 50–60–100, pivots about actuator axis 40, changing the angular relationship between the radial vector 112 and the actuator principal axis 110. Typically, an actuator arm assembly 50–60–100 will rotate through various angular relationships. The farthest inside position is often referred to as the Inside Position. The position where radial vector 112 approximately makes a right angle with 110 is often referred to as the Middle Position. The farthest out position where the read-write head 100 accesses disk surface 12 is often referred to as the Outside Position.
The primary wind direction 120 is essentially tangential, or perpendicular to the radial vector 112. As illustrated in FIG. 2C, the primary wind direction 120 and principal actuator axis 110 are not necessarily parallel.
To summarize, what is needed a way to minimize air flow induced turbulence around the read-write head while accessing a rotating disk surface.